Systemic sclerosis/scleroderma is a chronic autoimmune disease of unknown etiology characterized by altered humoral and cell-mediated immunity, and excessive deposition of collagen by fibroblasts in viscerae and skin. Cutaneous monocyte influx, adhesion, activation and differentiation into TGFbeta1-producing cells are thought to be (Scl GVHD). Hypothesis: A naturally occurring antagonist to TGFbeta, latency associated peptide (LAP) can inhibit fibrosis in animals with Scl GVHD when administered exogenously as recombinant protein, or as gene therapy with over-expressed LAP gene product delivered in vivo by transduced monocytes. Focused in vivo interventions can be evaluate din skin by morphologic studies, immunostaining and flow cytometry studies for monocytes, RT/PCR for TGF-beta1, and RNase protection assays for proalpha1(I) collagen mRNA. Our preliminary data are promising, showing recombinant LAP peptide prevents cutaneous fibrosis in mice with SCL GVHD. Aim I: What are the parameters and conditions for optimum in vivo inhibition of skin fibrosis by exogenous recombinant LAP peptide? Aim II: Can mouse bone marrow stem cells be transduced in vitro with a retroviral construct containing green fluorescent protein for detection and LAP and then driven in vitro to differentiate into functional monocytes? Aim III: After transfer to recipient mice, can these transduced monocytes survive in detectable numbers and home to skin? Can they over-express latency associated peptide in vivo, and inhibit the fibrosing process in animals with Scl GVHD? These proposed experiments have high relevance to our understanding of the basic monocyte biology, to TGFbeta-driven fibrosis in the animal model and in the autoimmune disease scleroderma, and potentially to the treatment of scleroderma and human graft versus host disease. Development of this novel monocyte- delivered immuno therapy can also be treated to treatment of other inflammatory disorders and of cancers.